Patent GB-595817-A (GB)
Title: Improvements in a grinding apparatus
IPC: B24B7/16
Filed: 1945-07-09
Abstract: 595,817. Grinding-machines. BURGESS, A. F. (Wellman Co., S. K.). July 9, 1945, No. 17452. [Class 60] In a grinding-machine, the grinding disc is rotated about one axis and a work-holding chuck is rotatable about another axis at right angles thereto, the chuck being movable for feed purposes along its axis of rotation, under the control of hydraulic means which cause the feed movement to be reduced as the grinding operation nears completion. As shown, the work is held on a rotary vacuum chuck 96 for presentation to a grinding-disc 21, feed being effected by admitting a pressure fluid, e.g. lubricating oil, to a cylinder space 70 surrounding the rotating chuck-carrying spindle 164 which serves also as an axially movable plunger. The lift of the spindle is limited by a stop sleeve 80 having a bevelled lower face 137 which engages a bevelled shoulder 139 on the spindle 164 which, above the shoulder is journalled in the sleeve 80, leakage of oil being minimized by grooves 100. The sleeve 80 is axially adjustable by rotation of a worm gear 148 secured thereto, the gear being threaded at 141 on the casing 14 and being rotated by a worm which is journalled in a bracket 156 pivoted to the casing at 157 and retained in meshing position by a turn-button 161. Disengagement of the worm permits quick adjustment of the sleeve 80. The spindle 164 has a reduced lower part 164a which, when the spindle rises due to admission of pressure fluid, becomes progressively more effective in slowing down the rate of ascent of the spindle. Towards the end of the rise, the rate is further slowed by the dashpot action of a band 189 which surrounds, and is secured to, the bevelled shoulder 139 and is housed, at the end of the rise, in a rabbet 191 in the outer surface of the sleeve 80. The spindle 164 is driven by a pulley 85 which is of sufficient width to accommodate the rise and fall of the spindle. Vacuum is applied to the work through an axial bore 105 in the spindle and branching passages 105a in the spindle leading to an annular recess 90 connected to passages 104 in the chuck body 88 between which and a work-receiving plate 17 a vacuum space 97 is formed. The work may be centred on the chuck by a central adapter 98 and rests on holes leading from the vacuum space 97. The bore 105 is connected to the vacuum source by a flexible pipe 118, the supply being under the control of a three-way valve 123 operated by a handle 125 so that the chuck may be connected to vacuum, or to atmosphere for release of the work, or to an air pressure source for more positive release and cleaning. The grinding-wheel 21 is driven by a motor and belting 20b and is journalled in a housing 19 adjustable, axially of the wheel, along slides by rack-and-pinion means. The housing 19, between spaced bearings for the wheel shaft, is supplied with oil from the system supplying the cylinder 70 which includes a tank 167, a pump 18, a byepass for returning excess oil to the tank and control valve means. Oil collecting in the space 146 above the sleeve 80 is taken back to the tank 167 by passages 193 via the space 164 and a drain pipe 195 connected thereto. A coolant may be supplied to the work, e.g. a pump may supply a pipe 196 and nozzle 197 and the coolant may be collected in a trough 198. A shield 20U keeps coolant from the moving parts. Air may be used as a coolant, in which case atmospheric air is drawn into an exhaust conduit through bifurcations straddling the work, the dust being thus drawn off. The work-holder assembly is mounted for vertical adjustment by slides and screws 214.